Durability of Constrained Liners in Revision THA
The indications for treating total hip arthroplasty (THA) dislocations by cementing a constrained polyethylene liner into a well-fixed, retained acetabular component at the time of revision are narrow. That’s largely due to concerns about the durability of the resulting acetabular construct. Now, thanks to a study by Brown et al. in the April 3, 2019 issue of JBJS, hip surgeons have some hard data about the long-term outcomes of this approach.
After reviewing 125 cases in which a constrained liner was cemented into a retained, osseointegrated acetabular component during revision THA, with a mean follow-up of 7 years, the authors found that:
- Survivorship free from revision for instability was 86% at 5 years and 81% at 10 years. The cumulative incidence of instability at 7 years was 18%.
- Survivorship free from aseptic acetabular component revision was 78% at 5 years and 65% at 10 years. The most common failure mechanism was dissociation of the constrained liner from the retained component.
- Harris hip scores (HHS) did not improve significantly after revision. This finding is consistent with prior research that shows better post-revision HHS scores in patients whose revisions include the entire acetabular component.
- Position of the retained cup did not affect implant survivorship or risk of dislocation.
The authors mention alternative strategies for reducing the risk of dislocation after revision THA, such as the use of large-diameter heads and dual-mobility constructs. Still, they conclude that this constrained-liner approach, in the setting of a relatively well-positioned acetabular component, is a viable and durable THA revision option, especially for those “with a compromised abductor mechanism, recurrent instability, [and] a well-fixed and well-positioned acetabular component, for whom an acetabular revision would not be tolerated.”
Patient-Specific Instruments’ Effects on TKA Revision
Whenever we introduce new technology or techniques in hopes of improving orthopaedic surgery, at least one of two criteria should be met: The new technology should improve the outcome at a maintained cost, or it should decrease cost while maintaining at least an equivalent outcome. If neither of these conditions is met, we need to think twice about adopting it. To help us answer these “value” questions, we need relevant data. This is why studies such as the one by McAuliffe et al. in the April 3, 2019 issue of The Journal are so important.
The authors use the Australian Orthopaedic Association National Joint Replacement Registry to compare the rate of revision between 3 types of primary total knee arthroplasty (TKA):
- Those performed with image-derived instrumentation (IDI, i.e., patient-specific cutting jigs)
- Those performed using computer navigation
- Those using neither technology
McAuliffe et al. found no significant differences between groups in terms of cumulative percent revision at 5 years. Subgroup analysis revealed a higher rate of revision (hazard ratio [HR] 1.52, p = 0.01) for the IDI group relative to the computer-navigated group when patients were ≤65 years old. In addition, the IDI group had a much higher rate of patellar revision when patients received posterior-stabilized knees (HR of 5.33 when compared with the computer-navigated group, and HR of 4.16 when compared with the neither-technology group).
This study seems to suggest that whatever the benefits of IDI may be in terms of attaining a “proper” mechanical axis during TKA, IDI does not translate into a lower revision rate. And when these revision data are viewed in the face of the added costs associated with IDI, it makes little sense to advocate for the widespread use of this technology for TKA at this time.
While this study focused on TKAs, the take-home message can be extended. Orthopaedic surgery is by nature complex, requiring that multiple steps be performed in harmony to produce an optimal outcome. It is easy for us to focus on (and measure) a couple of key outcome variables and base our opinions of a technique’s or technology’s success on such findings. But when it comes to “novel” techniques and technological “breakthroughs,“ we need a lot of data on many different variables before we can make meaningful conclusions, change our practice, and advise our patients.
Chad A. Krueger, MD
JBJS Deputy Editor for Social Media
Benchmark Data on Aseptic Revision after Knee Replacement
The main advantage of joint registries is their large number of recorded procedures, ideally with very few patient “types” not represented in the database. This is the case with the Australian Orthopaedic Association National Joint Replacement Registry, which includes data on almost 100% of all joint replacements performed in Australia since 2002. In the February 20, 2019 issue of The Journal, Jorgenson et al. analyze almost 6,000 major aseptic total knee arthroplasty (TKA) revisions from a cohort of 478,000 primary TKAs registered between 1999 and 2015. This analysis provides robust benchmark data for patients and surgeons, although it comes too late for the 3% of patients who required such a revision surgery within the 15-year study period.
The authors found that fixed bearings were revised for aseptic reasons at a significantly lower rate than mobile bearings (2.7% vs 4.1%, respectively) and that patients <55 years old had an almost 8-fold higher revision rate compared to patients ≥75 years old ( 7.8% versus 1.0%, respectively). The study also found lower aseptic revision rates with minimally stabilized total knee prostheses compared to posterior-stabilized prostheses, and higher aseptic revision rates with completely cementless fixation relative to either hybrid or fully cemented fixation. These are valuable data for arthroplasty surgeons in terms of selecting implants and surgical techniques and for preoperative counseling of patients—especially younger ones. While many of these findings have been previously reported, these registry-based results add significant strength to published data.
Ideally, data such as these would be controlled for confounding variables such as surgeon experience and additional patient-specific variables such as activity demands and medical comorbidities. Still, these data provide useful prosthesis-specific factors for shared decision making with patients. We look forward to more helpful information from this and other national joint registries and encourage the continued growth of similar registries in other subspecialties.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
Physical Parameters Beyond BMI Affect TKA Outcomes
It is well established that obese patients who undergo total joint arthroplasty have increased risks of complications and infections. But what about folks who are not obese, but are just generally large? Do they also have increased post-arthroplasty complications, compared to their smaller counterparts? That is the question Christensen et al. explored in a registry-based study in the November 7, 2018 edition of JBJS.
In addition to BMI, the authors examined 3 other physical parameters—body surface area, body mass, and height—to determine whether these less-studied characteristics (all contributing to “bigness”) were associated with an increased rate of various adverse outcomes, including mechanical failure and infection, after primary total knee arthroplasty (TKA). They evaluated data from more than 22,000 TKAs performed at a single institution and found that the risk of any revision procedure or revision for a mechanical failure was directly associated with every 1 standard deviation increase in BMI (Hazard Ratio [HR], 1.19 and 1.15, respectively), body surface area (HR, 1.37 and 1.35, respectively), body mass (HR, 1.30 and 1.27, respectively), and height (HR, 1.22 and 1.23, respectively). In this study, 1 standard deviation was equivalent to 6.3 kg/m2 for BMI, 0.3 m2 for body surface area, 20 kg for body mass, and 10.5 cm for height.
These findings, while not all that surprising, are enlightening nonetheless. The study shows that increasing height has a greater negative impact on TKA outcomes than previously thought. While I spend a lot of time counseling patients with high BMIs about the increased risks of undergoing a TKA (and while such patients can take certain actions to lower their BMI prior to surgery), I do not spend nearly as much time counseling patients who are much taller than normal about their increased risks (and height is not a modifiable risk factor). Nor do I spend much time thinking about a patient’s overall body mass or body surface area in addition to their BMI. This study will remind me not to overlook these less commonly examined physical parameters when discussing TKA with patients in the future.
Chad A. Krueger, MD
JBJS Deputy Editor for Social Media
Structural Allografts Can Work for Acetabular Defects in THA
Allograft bone is used often in orthopaedic surgery. However, the use of structural allografts to address large acetabular defects in total hip arthroplasty (THA) is not common. But it may become more so in light of the study by Butscheidt et al. in the August 15, 2018 issue of JBJS. The authors add to our knowledge about these relatively rare procedures by evaluating the incorporation of structural acetabular allografts into host bone among 13 complete pelvic explants containing allograft that had been in place for a mean of 13 years.
Using sophisticated imaging and histological techniques, the authors found that in 10 out of the 13 specimens retrieved, 100% of the interface was characterized by direct contact and additional overlap of the allograft bone and the host bone. The remaining 3 allografts showed direct contact along 25% to 80% of the interface. The authors found no correlation between ingrowth of the host bone into the allograft and the amount of time the allograft had spent in situ, leading them to surmise that “a large proportion of the incorporation process may be completed within the first weeks.”
Large, structural allografts are not commonly used for acetabular reconstructions, as most surgeons seem to favor other options. (See the JBJS Clinical Summary on “Managing Acetabular Defects in Hip Arthroplasty.”) While a postmortem study of 13 cases may not be “practice-changing,“ the Butscheidt et al. analysis does provide some detailed clarity as to what surgeons can expect from these large allograft reconstructions in terms of incorporation with host bone. Obviously, one limitation of this study is that structural allografts that never incorporated with the host bone probably failed early and would not be available for analysis in a long-follow-up retrieval study.
Chad A. Krueger, MD
JBJS Deputy Editor for Social Media
More Evidence of Patient Benefits with Cross-Linked Polyethylene
In an OrthoBuzz post last year titled “Has Conventional Polyethylene Become Obsolete?,” we featured results from a small randomized trial that documented much-improved implant survival over 10 years with acetabular components made from cross-linked polyethylene (XLPE) compared with conventional polyethylene (CPE). In the August 1, 2018 issue of The Journal, we find further corroboration of the benefits realized by patients who receive XLPE acetabular components.
deSteiger et al. analyzed registry data involving more than 240,000 total hip arthroplasty (THA) patients and found markedly lower revision rates in those who received XPLE rather than CPE acetabular components. At a mean follow-up of 16 years, the cumulative percentage of revisions was 6.2% in the XPLE group versus 11.7% in the CPE group. Among patients <55 years of age at the time of THA, at 7 years there was a five-fold increase in revision rates for procedures done with CPE compared to those done with XLPE.
Because the authors observed that the between-group differences in revision rates became more pronounced over time, it is possible that this difference will continue to grow as more data is gathered. When we consider the vast number of THAs performed around the world each year, this XLPE-related decrease in revision rate could have a beneficial impact on millions of patients.
The documented success so far of XPLE is a clear case where understanding the nature of the original problem (polyethylene wear) and applying consistent and innovative research to find a solution have allowed patients worldwide to reap the benefits associated with THA, with some assurance that their hip replacement may, in fact, last for their rest of their life.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
Prescribing Opioids: Smallest Dose for Shortest Time
Some people are tired of reading and hearing about the opioid crisis in America. When this topic comes up at meetings, there are rumblings in the crowd. When it’s brought up during hospital safety briefings, there are not-so-subtle eye-rolls, and occasionally I hear frank assertions of “enough already” when new information on the topic appears in the literature. Yet, as two studies in the July 18, 2018 edition of JBJS highlight, this topic is not going away any time soon. And for good reason. We are only starting to scratch the surface of the serious unintended consequences—beyond the risk of addiction—from overly aggressive prescribing and consumption of narcotics.
The first article, by Zhu et al., directly addresses the topic of overprescribing by doctors in China. The authors evaluated how many opioid pills were given to patients who sustained fractures that were treated nonoperatively. The mean number of opioid pills patients reported consuming (7.2) was less than half the mean number prescribed (14.7). More than 70% of patients did not consume all the opioid pills they were prescribed, and 10% of patients consumed no opioids at all. Zhu et al. conclude that “if opioids are used [in this setting], surgeons should prescribe the smallest dose for the shortest time after considering the injury location and type of fracture or dislocation.”
The second article, by Weick et al., underscores the patient-outcome and societal impact of opioid use prior to total hip and knee arthroplasty. Patients from North America who consumed opioids for 60+ days prior to their joint replacement had a significantly increased risk of revision at both the 1-year and 3-year postoperative follow-ups, compared to similar patients who were opioid-naïve before surgery. Similarly, patients who used opioids for 60+ days prior to undergoing a total hip or knee arthroplasty had a significantly increased risk of 30-day readmission, compared to patients who were opioid-naïve. All these differences held when the authors made adjustments for patient age, sex, and comorbidities—meaning that tens of thousands of patients each year can expect to have worse outcomes (and add a large cost burden to the health care system) simply by being on opioid medications for two months preoperatively.
These articles address two very different research questions in two very different regions of the world, but they help expose the chasm in our knowledge surrounding opioid use and misuse. We have been prescribing patients more narcotics than they need while just starting to recognize the importance of minimizing opioid use preoperatively in an effort to maximize surgical outcomes. These two competing impulses emphasize why further opioid-related studies are important. While continuing to look at the negative effects these medications can have on patients, we have to take a hard look at our contribution to the problem.
Chad A. Krueger, MD
JBJS Deputy Editor for Social Media
Predicting Failure of Femoral Neck Fixation
OrthoBuzz occasionally receives posts from guest bloggers. This guest post comes from Matthew Herring, MD, in response to a recent study in the Journal of Orthopaedic Trauma.
With many problems in orthopaedics, the best management options are still being debated. The treatment of femoral neck fractures is one such problem. Surgeons have several available options: cancellous screws (CS), a sliding hip screw (SHS), hemiarthroplasty, and total hip arthroplasty. The recently completed Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) randomized trial sought to offer insight on those treatment modalities.1 The study enrolled 1,079 patients with low-energy femoral neck fractures and randomized them into treatment with CS or SHS.
In a follow-up study published in the May 2018 edition of the Journal of Orthopedic Trauma, Sprague et al. analyzed FAITH data to identify predictors of revision surgery during 24 months after surgical fixation of a femoral neck fracture.2 Based on previously published studies, the authors identified 15 factors a priori that may be associated with revision surgery . Among the more than 800 patients in the FAITH cohort who had complete follow-up data, 191 (23%) underwent revision surgery and were included in the analysis. Proportional hazard modeling identified 5 factors associated with revision surgery: female sex (hazard ratio [HR], 1.79), body mass index (HR, 1.19—a 19% increased risk of revision for every 5-point increase in BMI), displaced fracture (HR, 2.16), Pauwels type III configuration (HR, 2.13 relative to type II), and poor implant positioning (HR, 2.70). In addition, prefracture dependence on assistive devices for ambulation was significantly associated with a risk of conversion to arthroplasty (p = 0.04), although a hazard ratio was not reported.
These important findings may help guide our decision making for the treatment of femoral neck fractures. First, male patients may be better candidates for surgical fixation of neck fractures than female patients, which probably relates to sex differences in bone density. Thinner patients also may be better candidates for femoral neck fixation, while arthroplasty may be the more reliable option for high-BMI patients.
Second, we have to pick the right fractures to fix. As is well described elsewhere in the literature, a more vertical fracture line (>50°) is more likely to fail with fixation. Additionally, patients with displaced fractures face a significantly higher risk of revision surgery and may be poor candidates for fixation.
Arguably, the most important modifiable risk factor for revision surgery is surgical technique. Unfortunately (and fortunately), in the FAITH study there were too few malreductions to investigate this variable in detail. However, poor implant positioning—defined as prominent screws at the lateral cortex, screw penetration, and lag screws positioned too high—was strongly associated with an increased risk of revision surgery.
It goes without saying, but well-placed implants perform better.
Matthew Herring, MD is a senior orthopaedic resident at the University of Minnesota and a member of the JBJS Social Media Advisory Board.
References
- Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) Investigators. Fracture fixation in the operative management of hip fractures (FAITH): an international, multicentre, randomised controlled trial. Lancet. 2017;389(10078):1519-1527.
- Sprague S, Schemitsch EH, Swiontkowski M, et al. Factors Associated With Revision Surgery After Internal Fixation of Hip Fractures. J Orthop Trauma. 2018;32(5):223-230.
JBJS 100: Infection Prevention and Hip Replacement Rates
Under one name or another, The Journal of Bone & Joint Surgery has published quality orthopaedic content spanning three centuries. In 1919, our publication was called the Journal of Orthopaedic Surgery, and the first volume of that journal was Volume 1 of what we know today as JBJS.
Thus, the 24 issues we turn out in 2018 will constitute our 100th volume. To help celebrate this milestone, throughout the year we will be spotlighting 100 of the most influential JBJS articles on OrthoBuzz, making the original content openly accessible for a limited time.
Unlike the scientific rigor of Journal content, the selection of this list was not entirely scientific. About half we picked from “JBJS Classics,” which were chosen previously by current and past JBJS Editors-in-Chief and Deputy Editors. We also selected JBJS articles that have been cited more than 1,000 times in other publications, according to Google Scholar search results. Finally, we considered “activity” on the Web of Science and The Journal’s websites.
We hope you enjoy and benefit from reading these groundbreaking articles from JBJS, as we mark our 100th volume. Here are two more:
Prevention of Infection in Treatment of 1,025 Open Fractures of Long Bones
R B Gustilo and J T Anderson: JBJS, 1976 June; 58 (4): 453
While “best practices” for managing open long-bone fractures have changed since this landmark study was published, the Gustilo-Anderson classification still correlates well with the risk of infection in patients with comorbid medical illnesses and other complications. It remains widely accepted for research and training purposes, and it provides commonly used basic language for communicating about open fractures.
Rates and Outcomes of Primary and Revision Total Hip Replacement in the US Medicare Population
N N Mahomed, J A Barrett, J N Katz, C B Phillips, E Losina, R A Lew, E Guadagnoli, W H Harris, R Poss, J A Baron: JBJS, 2003 January; 85 (1): 27
Analyzing Medicare claims data between July 1, 1995 and June 30, 1996, the authors of this prognostic study claimed it was “the first population-based study of the rates of revision total hip replacement and its short-term outcomes.” In the last 10 years alone, more than 5,000 studies on revision THA have been published in PubMed-indexed journals, including this 2012 JBJS study, which examined THA revision risk in the same Medicare cohort over 12 years.
JBJS 100: Controlling Bone Growth and Revision THA Stats
Under one name or another, The Journal of Bone & Joint Surgery has published quality orthopaedic content spanning three centuries. In 1919, our publication was called the Journal of Orthopaedic Surgery, and the first volume of that journal was Volume 1 of what we know today as JBJS.
Thus, the 24 issues we turn out in 2018 will constitute our 100th volume. To help celebrate this milestone, throughout the year we will be spotlighting 100 of the most influential JBJS articles on OrthoBuzz, making the original content openly accessible for a limited time.
Unlike the scientific rigor of Journal content, the selection of this list was not entirely scientific. About half we picked from “JBJS Classics,” which were chosen previously by current and past JBJS Editors-in-Chief and Deputy Editors. We also selected JBJS articles that have been cited more than 1,000 times in other publications, according to Google Scholar search results. Finally, we considered “activity” on the Web of Science and The Journal’s websites.
We hope you enjoy and benefit from reading these groundbreaking articles from JBJS, as we mark our 100th volume. Here are two more:
Control of Bone Growth by Epiphyseal Stapling: A Preliminary Report
W P Blount and G R Clarke: JBJS, 1949 July; 31 (3): 464
This 14-page, amply illustrated article was the oldest paper selected by Kavanagh et al. in their 2013 JBJS bibliometric analysis of the 100 classic papers of pediatric orthopaedics. Blount and Clarke proved definitively that long-bone growth could be arrested by appropriately timed epiphyseal stapling and that growth would resume after staple removal. Their work spared many children with linear or angular leg deformities—often a result of polio—from the risk of more invasive operative methods.
Epidemiology of Revision Total Hip Arthroplasty in the US
K J Bozic, S M Kurtz, E Lau, K Ong, T P Vail, D J Berry: JBJS, 2009 January; 91 (1): 128
Fast forwarding 60 years from the Blount and Clarke study, we arrive at this epidemiological analysis of >51,000 revision hip replacements. The findings from this 2009 Level II prognostic study provided information that has guided THA research, implant design, and clinical decision-making throughout the past decade.
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